[GIS] How to add buttons to QT ui for qgis feature forms to loop through attributes

loopqgisqt

I'm looking for a bit of guidance.

I'm happy creating a standard feature form using QT designer (as excellently documented here) for QGIS but I was wondering how you add a forward and back button to a feature form, so that it would loop through all the identified features in QGIS?

Below is a mockup of what I'd like to achieve but need some help. You'll see that I haven't added in any 'line edits' in my tabs and that was purely to produce a mockup for the purposes of this question.

enter image description here

Best Answer

This particular way is currently not possible with QGIS (at least not without an advanced plugin)

However, an alternative approach be almost what you want without any python at all and without adding custom buttons.

Select some features
Open the attribute table and switch to form view (See highlighted button in picture).
Choose "Show Selected Features" and navigate with the help of the list on the left.

Feature form, Dual View

QGIS 2.0

from PyQt4.QtCore import *
from PyQt4.QtGui import *

id_flaecheField = None
id_fotoField = None

myDelToolFeature = None
myDelToolLayer = None

def formOpen(dialog,layer,feature):
    global myDelToolFeature
    global myDelToolLayer

    myDelToolFeature = feature
    myDelToolLayer = layer

    id_fotoField = dialog.findChild(QComboBox,"id_foto")
    id_flaecheField = dialog.findChild(QComboBox,"id_flaeche")
    buttonDelete= dialog.findChild(QPushButton,"pushButton")
    buttonDelete.clicked.connect(delete)

def delete():
    # Delete the feature
    myDelToolLayer.deleteFeature( myDelToolFeature.id() )

QGIS 1.8

from PyQt4.QtCore import *  
from PyQt4.QtGui import *  

from qgis.core import QgsMapLayerRegistry

id_flaecheField = None
id_fotoField = None

myDelToolFeatureId = None
myDelToolLayer = None

def formOpen(dialog,layerid,featureid):  
    global myDelToolFeatureId
    global myDelToolLayer

    myDelToolFeatureId = featureid
    myDelToolLayer = layerid

    id_fotoField = dialog.findChild(QComboBox,"id_foto")
    id_flaecheField = dialog.findChild(QComboBox,"id_flaeche")
    buttonDelete= dialog.findChild(QPushButton,"pushButton")
    buttonDelete.clicked.connect(delete)

def delete():
    # Get the layer from the registry
    layer = QgsMapLayerRegistry.instance().mapLayer( myDelToolLayer )
    # Delete the feature
    layer.deleteFeature( myDelToolFeatureId )

MapBasic – How to Loop Through All Columns in a Table/Layer Getting All Data for a Row/Feature in MapBasic

You can use this structure to loop through the columns of a table.

Dim sCol As String
Dim aCol As Alias
Dim nCol As Integer
For nCol = 1 To TableInfo(sLayer, TAB_INFO_NCOLS)
   sCol = ColumnInfo(sLayer, "COL" & nCol, COL_INFO_NAME)
   aCol = sLayer & "." & sCol
Next

This will loop through the columns of the table sLayer and store the name in an Alias variable. The next step is to transfer the values from the column to a variable and to be able to write these to an SVG file for other systems to read them back.

To be able to do that in a nice manner you need to convert the data to something that will make sense to this other system.

Here is an example of how that can be done including the loop mentioned above:

Dim sCol As String
Dim aCol As Alias
Dim nCol As Integer
For nCol = 1 To TableInfo(sLayer, TAB_INFO_NCOLS)
   sCol = ColumnInfo(sLayer, "COL" & nCol, COL_INFO_NAME)
   aCol = sLayer & "." & sCol
   sValue = ""
    Do Case ColumnInfo(sLayer, sCol, COL_INFO_TYPE)
       Case COL_TYPE_CHAR
          sValue = aCol
       Case COL_TYPE_INTEGER, COL_TYPE_SMALLINT, COL_TYPE_LOGICAL
          sValue = Str$(aCol)
       Case COL_TYPE_FLOAT, COL_TYPE_DECIMAL
          'Converting decimal number to locale formatted numbers  
          '(Windows Regional Settings)
          sValue = FormatNumber$(aCol)
       Case COL_TYPE_DATE
          If aCol Then
             'Converting dates to locale formatted dates
             '(Windows Regional Settings)
        sValue = FormatDate$(aCol)
          End If
       Case COL_TYPE_TIME
          If aCol Then
             'Converting Time to 24 hour clock
             sValue = FormatTime$(acol, "HH:mm:ss")
          End If
       Case COL_TYPE_DATETIME
          If aCol Then
             'Converting dates to locale formatted dates
             '(Windows Regional Settings)
             'Converting Time to 24 hour clock
             sValue = FormatDate$(aCol) & " " & FormatTime$(GetTime(acol), "HH:mm:ss")
          End If
    End Case
    Next

If you want to add a loop that runs through all the records of the layer too, you will have to wrap the loop above into another Do Until..Loop structure. In this structure, you use the Fetch statements to first fetch the first and then continue to fetch the next record until the cursor is at End Of Table (EOT).

Here's an example of that:

Dim sCol As String
Dim aCol As Alias
Dim nCol As Integer

Fetch First From sLayer
Do Until EOT(sLayer)
   For nCol = 1 To TableInfo(sLayer, TAB_INFO_NCOLS)
      sCol = ColumnInfo(sLayer, "COL" & nCol, COL_INFO_NAME)
      aCol = sLayer & "." & sCol
      sValue = ""
       Do Case ColumnInfo(sLayer, sCol, COL_INFO_TYPE)
          Case COL_TYPE_CHAR
             sValue = aCol
          Case COL_TYPE_INTEGER, COL_TYPE_SMALLINT, COL_TYPE_LOGICAL
             sValue = Str$(aCol)
          Case COL_TYPE_FLOAT, COL_TYPE_DECIMAL
             'Converting decimal number to locale formatted numbers  
             '(Windows Regional Settings)
             sValue = FormatNumber$(aCol)
          Case COL_TYPE_DATE
             If aCol Then
                'Converting dates to locale formatted dates
                '(Windows Regional Settings)
                 sValue = FormatDate$(aCol)
             End If
          Case COL_TYPE_TIME
             If aCol Then
                'Converting Time to 24 hour clock
                sValue = FormatTime$(acol, "HH:mm:ss")
             End If
          Case COL_TYPE_DATETIME
             If aCol Then
                'Converting dates to locale formatted dates
                '(Windows Regional Settings)
                'Converting Time to 24 hour clock
                sValue = FormatDate$(aCol) & " " & FormatTime$(GetTime(acol), "HH:mm:ss")
             End If
       End Case
    Next  
    Fetch Next From sLayer
Loop

Hope that helps

Best Answer

Related Solutions

[GIS] How to add a delete button to feature forms

QGIS 2.0

QGIS 1.8

MapBasic – How to Loop Through All Columns in a Table/Layer Getting All Data for a Row/Feature in MapBasic

Related Question